Heating, ventilation, and air conditioning systems (sometimes referred to as HVAC systems) are commonly used to provide ventilation, reduce air infiltration, maintain pressure relationships between spaces, and control thermal comfort and indoor air quality in residential and commercial structures, such as homes and office buildings. An HVAC system's ability to satisfactorily provide these benefits may depend on adequate air intake, air return, and airflow. Proper and efficient airflow may also save energy, decrease operational costs, and increase the life of the HVAC system.
However, methods and components commonly used for HVAC system intake and return air pathways have some disadvantages. Moreover, meeting the requirements from government regulations and manufacturer's specifications using currently available industry methods and components can be challenging.
HVAC systems used to be commonly installed directly to a floor and the intake and return air ducts connected to and directed air into the lateral side of the furnace unit. However, this method of installation and directing of airflow has several disadvantages. One disadvantage is that the furnace unit's metal frame is more likely to rust from exposure to moisture when mounted directly on the floor. Another disadvantage is that directing intake and return air through the lateral side of a furnace unit does not allow for maximum airflow efficiency.
Some attempts have been made to overcome these problems by installing HVAC systems on bases. Bases currently available are typically made of galvanized aluminum sheet metal and allow the HVAC system to be installed about ten inches above the floor. These aluminum sheet metal bases typically attempt to increase airflow by directing intake and return air into the furnace unit through the bottom side of the furnace instead of through the lateral side of the furnace. These aluminum sheet metal bases are typically configured to receive a return air duct on the top side of the base so that airflow travels down through the top of and into the base where the air subsequently travels underneath the furnace unit and then up and into the furnace unit. However, there are a number of disadvantages to these types of HVAC bases and methods for directing airflow in an HVAC system.
One disadvantage with currently available bases is that air intake and return may be limited to traveling through the bottom side of the furnace unit and therefore may not permit maximum airflow efficiency. Also, HVAC systems installed in conjunction with currently available bases may be more prone to premature failure of the furnace and central air units due to the airflow limitations.
Another problem is that a narrower filter box (e.g., one inch filter rack) commonly has to be used when an HVAC system is installed on a base in a home having standard eight foot ceilings, because the filter box is installed horizontally between the top of the base and the bottom side of the furnace and the HVAC system may not have enough head room to permit installation of a wider filter box (e.g., a five inch filter rack). Narrower filter racks typically do not filter air as effectively as wider filter racks and therefore may negatively affect the quality of air being circulated in a home or business.
Another problem is that sheet metal bases commonly bow from the weight of the furnace mounted above the base and the magnitude of the bow may increase over time. Furthermore, the metal base and furnace frame may be disposed to rust or corrosion at metal-to-metal connection points between the furnace and the base. Moreover, a metal base may be disposed to rust and corrosion on its bottom side from exposure to moisture on the floor.
Installing HVAC systems on bases currently available can also be labor intensive and require many steps to configure the HVAC system with the base. For example, persons installing HVAC systems commonly have to size and cut a hole in the top of the base to fit the filter box and furnace that are to be mounted thereon. Moreover, there is a risk of multiple potential leak points when installing and HVAC system on a sheet metal base, which may increase inefficiencies in airflow if not properly sealed. Ensuring that these potential leak points are properly sealed can be labor intensive.
It is thus desirable to have an in a durable HVAC base and air return system that improves airflow and efficiency, reduces time and labor to install, and facilitates good air filtering.